In the applicant's earlier application with file number 10 2011 002 904.4, an add-on module connected with a basic transmission is disclosed, which is supplied with lubricating oil coming from the basic transmission, i.e. which is connected to the lubricating oil circuit of the basic transmission by means of an inflow line and a return line. The add-on module has a connecting shaft, which is mounted on one side in a housing of the module and on the other side by a plug-in connection to the input shaft or driveshaft of the basic transmission. The plug-in connection, designed in the form of drive gearing, and the roller bearing, are the two lubrication points which must essentially be supplied with lubricating oil. In the approach adopted by the earlier application it is provided that the two lubrication points are positioned one behind the other in the oil supply line so that oil flows first through the drive gearing and then through the bearing. By way of an axis-parallel return bore the oil is returned again to the area of the basic transmission. In the separation area between the transmission input shaft and the connecting shaft an oil transfer element is provided, which separates the oil inflow from the oil return.